BIOL 101: Unit 2 Vocabulary List

A complete set of vocabulary flashcards covering macromolecule categories, cell structures, and plasma membrane dynamics from BIOL 101 Unit 2.

Macromolecule

A large molecule formed by joining smaller organic molecules, including carbohydrates, lipids, proteins, and nucleic acids.

Monomer

A repeating subunit or structural building block that covalently bonds to form a polymer.

Polymer

A long molecule consisting of many similar or identical monomers linked together by covalent bonds.

Dehydration reaction

A chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule.

Hydrolysis

A chemical reaction that breaks bonds between monomers by the addition of a water molecule.

Carbohydrates

Biological macromolecules including sugars, monosaccharides, disaccharides, and polysaccharides that serve as fuel and structural material.

Monosaccharide

The simplest carbohydrate monomer, such as glucose, serving as a building block for complex carbohydrates.

Aldose sugar

A sugar containing a carbonyl group at the end of the carbon skeleton.

Ketose sugar

A sugar containing a carbonyl group within the carbon chain.

Disaccharide

A double sugar consisting of two monosaccharides joined by a covalent bond, such as maltose, sucrose, or lactose.

Polysaccharide

A polymer of many monosaccharides, such as glycogen, starch, cellulose, or chitin.

Triglyceride

A lipid composed of three fatty acids linked to one glycerol molecule.

Phospholipid

An amphipathic lipid composed of glycerol, two fatty acids, and a phosphate group, forming cell membrane bilayers.

Primary structure

The specific linear sequence of amino acids in a protein polypeptide chain.

Secondary structure

The localized coils or folds of a polypeptide chain, such as \text{\alpha}-helices and \text{\beta}-sheets, stabilized by hydrogen bonds.

α-helices

A delicate coil formed in a protein secondary structure, held together by hydrogen bonding between every fourth amino acid.

β-sheets

A secondary protein structure featuring two or more segments of the polypeptide chain lying side by side connected by hydrogen bonds.

Tertiary structure

The overall three-dimensional shape of a polypeptide resulting from interactions between amino acid R groups, including disulfide bonds.

Quaternary structure

The overall protein structure resulting from the aggregation of two or more polypeptide subunits.

Denaturation

A process in which a protein loses its native shape and structural integrity due to environmental changes in temperature, pH, or chemical conditions.

Nucleotide

The monomer of a nucleic acid, consisting of a 5-carbon sugar, a nitrogenous base, and a phosphate group.

Cell Theory

The fundamental biological concept stating that all living organisms are composed of cells and all cells come from pre-existing cells.

Prokaryotes

Organisms whose cells lack a membrane-enclosed nucleus and membrane-bound organelles.

Eukaryotes

Organisms whose cells contain a membrane-enclosed nucleus and specialized membrane-bound organelles.

Endomembrane system

The collection of membranes inside a eukaryotic cell including the nuclear envelope, rER, sER, Golgi, vesicles, lysosomes, and plasma membrane.

Rough ER (rER)

The portion of the endoplasmic reticulum studded with ribosomes on its outer surface, involved in protein synthesis and processing.

Smooth ER (sER)

The portion of the endoplasmic reticulum free of ribosomes, involved in lipid synthesis, carbohydrate metabolism, and detoxification.

Golgi

An organelle with flattened membranous sacs (cisternae) that modifies, sorts, and packages proteins for secretion or cellular transport.

Lysosomes

Membranous sacs of hydrolytic enzymes in animal cells used to digest macromolecules, perform phagocytosis, and undergo autophagy.

Mitochondria

Semiautonomous organelles that serve as the site of cellular respiration to produce energy.

Chloroplasts

Semiautonomous organelles found in plants and algae that capture light energy to perform photosynthesis.

Cytoskeleton

A network of protein fibers extending throughout the cytoplasm, consisting of microtubules, microfilaments, and intermediate filaments.

Fluid Mosaic Model

The structural model depicting the plasma membrane as a mosaic of protein molecules floating in a fluid phospholipid bilayer.

Amphipathic

Having both a hydrophilic region and a hydrophobic region, characteristic of phospholipids and membrane proteins.

Integral protein

A transmembrane protein embedded within the hydrophobic interior of the lipid bilayer.

Peripheral protein

A protein loosely bound to the surface of the plasma membrane and not embedded in the phospholipid bilayer.

Selective permeability

A property of biological membranes that allows some substances to cross more easily than others.

Passive transport

The movement of substances across a biological membrane down their concentration gradient without energy input.

Osmosis

The diffusion of free water across a selectively permeable membrane.

Active transport

The movement of a substance across a cell membrane against its concentration gradient, requiring cellular energy.

Na+/K+ pump

An electrogenic transport protein that actively moves $\text{Na}^+$ out of the cell and $\text{K}^+$ into the cell against their concentration gradients.

Exocytosis

The secretion of biological molecules by the fusion of vesicles with the plasma membrane.

Endocytosis

The cellular uptake of biological molecules and particulate matter via formation of new vesicles from the plasma membrane.

Receptor-mediated endocytosis

A specialized type of endocytosis where specific cell-surface receptor proteins bind target ligands before vesicle formation.